Halley’s Comet is a mathematical clock from space – 01/19/2021 – Marcelo Viana

When I returned to Brazil in 1986 to do my doctorate at the Impa (Institute for Pure and Applied Mathematics), one scientific topic dominated the headlines: the return of Halley’s comet. Rightly there were great expectations for the return of one of the most charismatic stars in the solar system. There were even those who registered the Halley brand to make money out of! In the end, the star went a little far and the look was less spectacular than expected.

But scientifically it was a historic event. It was the first comet observed by spacecraft such as the European Giotto, which confirmed that it was composed of a mixture of solids and volatile materials that are formed when the comet’s hair (atmosphere) and tail are approached sol. And Halley’s return once again demonstrated the remarkable power of mathematics to describe what surrounds us.

The story is long. The first reliable Halley record was made in 239 BC. Made by Chinese astronomers, but it is possible that they were made as early as 466 BC. By the Greeks and even 164 BC. BC and 87 BC Was noticed by the Babylonians. It is believed that the passage from 1301 influenced the depiction of the star of Bethlehem in the famous “Adoration of the Magi” by the Renaissance painter Giotto (hence the name of the space probe I mentioned).

However, it took some time for these phenomena to be related. Comets were seen as announcements of important facts and were considered to be atmospheric phenomena (Galileo Galilei himself defended this thesis). With the publication of Newton’s law of gravitation in 1687, the idea that these were celestial bodies in motion gained strength.

In 1705, the English astronomer Edmond Halley (1656–1742) observed that comets appeared at nearly identical intervals in 1531, 1607, and 1682, and suggested that they correspond to the same star, which would then return in 1758.

The French astronomers Clairaut, Lalande and Lepaute refined the calculations using Newton’s gravitational equations. His conclusions were brilliantly confirmed when the comet appeared in the sky in April 1759. Halley no longer lived to watch.

The fascination with comets in the scientific age is symbolized by the phrase attributed to the American writer Mark Twain: “I came with Comet Halley in 1835 and hope to go with it in 1910.” He died a day after the comet’s perihelion, that is, its maximum approach to the sun.

Halley was photographed for the first time in 1910. This phenomenon was spectacular, in part because the comet was “only” 22 million km from Earth, and the same would happen the next time in 2061. It’s worth the wait!

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